Rigid Flex Architecture against Two Boards and a Connector
Rigid-flex architecture eliminates discrete connector failures and signal discontinuities while reducing assembly labor, justifying higher bare-board costs.
Adhesive Free Polyimide
Material Integrity
Flexible laminates designed with direct metalisation or cast polyimide on copper eliminate the thick polymer adhesive layers found in conventional three-layer materials. Substrates constructed with adhesive free polyimide exhibit thinner profiles and lower moisture absorption than their adhesive-backed counterparts. These materials prevent the pad lifting and board delamination commonly caused by the thermal expansion of acrylic bonding agents during assembly.
They also permit the creation of finer line geometries because the surface of the polyimide is smoother than the adhesive interface.
Thermal Performance
Thermal degradation risks during lead-free soldering decrease when the weak acrylic layer is absent. Using adhesive free polyimide prevents the blistering and outgassing failures that occur during multi-stage reflow cycles. The resulting circuit assembly operates reliably at temperatures exceeding one hundred and fifty degrees Celsius.
Mechanical Endurance
Dynamic bending performance improves because the thinner cross-section reduces outer-fibre stress during tight folding. Incorporating adhesive free polyimide into dynamic applications prevents copper traces from work-hardening and fracturing. Standard three-layer boards often suffer trace breaks due to the shifting of traces within the soft adhesive layer under mechanical stress.
This material provides the mechanical endurance required for military and medical devices where constant flexing is expected. It achieves this by maintaining a rigid connection between the trace and substrate throughout millions of flexural cycles.